Mechanisms of MMP-Induced Malignancy in Breast Cells

描述（申请人提供）：基质金属蛋白酶（MMPs）是许多生理过程所必需的，但MMPs的不适当表达可促进肿瘤的发生和发展。 MMPs和恶性肿瘤之间关系的认识导致了广谱MMP抑制剂作为癌症治疗剂的临床试验，但结果令人失望。 临床试验的失败在很大程度上是由于MMP抑制剂抑制基本生理过程的倾向。 靶向肿瘤特异性MMP依赖性效应的治疗策略可能更有希望。 以前的研究和我们的初步数据表明，乳腺上皮细胞暴露于选定的基质金属蛋白酶导致细胞表面分子的裂解，刺激细胞产生活性氧（ROS）。 MMP依赖性ROS的产生导致细胞经历上皮-间充质转化（EMT），这是与转移进展相关的基本表型改变，并损害细胞基因组稳定性。 我们的长期目标是确定与MMP诱导的恶性转化相关的具体步骤，以确定潜在的治疗干预点。 为此，我们建议（1）确定刺激ROS发展的MMP蛋白水解靶点，（2）确定转录因子Snail和Twist在MMP/ROS诱导EMT中的作用，以及（3）确定MMP/ROS如何刺激基因组不稳定性。 在目标1中，通过MMPs切割E-钙粘蛋白的特定作用的研究将通过蛋白水解筛选补充额外/替代靶点。 在目标2中，我们将确定MMP诱导的因子负责蜗牛和扭曲的表达增加，并将解剖MMP诱导的EMT这些转录因子的相对作用。 在目标3中，我们将研究MMP/ROS如何通过刺激中心体扩增诱导细胞非整倍体和有丝分裂异常。 我们希望通过阐明MMPs诱导EMT和基因组不稳定性的事件链，我们将能够确定新的有希望的点，用于乳腺癌的治疗干预。

DESCRIPTION (provided by applicant): Matrix metalloproteinases (MMPs) are essential for many physiological processes, but inappropriate expression of MMPs can facilitate the development and progression of tumors. Recognition of the relationship between MMPs and malignancy led to clinical trials of broad-spectrum MMP inhibitors as cancer therapeutics, but the results were disappointing. The failure of the clinical trials was due in large part to the propensity of the MMP inhibitors to inhibit essential physiological processes. Therapeutic strategies that target tumor-specific MMP-dependent effects may prove more promising. Previous studies and our preliminary data show that exposure of mammary epithelial cells to selected MMPs causes cleavage of a cell surface molecule that stimulates cellular production of reactive oxygen species (ROS). MMP-dependent production of ROS causes cells to undergo epithelial-mesenchymal transition (EMT), a fundamental phenotypic alteration associated with progression to metastasis, and compromises the cellular genomic stability. Our long-term objective is to identify the specific steps associated with the MMP-induced malignant transformation so as to determine potential points for therapeutic intervention. To do this, we propose (1) to identify the proteolytic target of MMPs that stimulates the development of ROS, (2) to determine roles of transcription factors Snail and Twist in MMP/ROS-induction of EMT, and (3) to define how MMP/ROS stimulate genomic instability. In Aim 1, investigations of the specific role of cleavage of E-cadherin by MMPs will be supplemented by a proteolytic screen for additional/alternative targets. In Aim 2, we will identify the MMP-induced factors responsible for the increased expression of Snail and Twist, and will dissect the relative role of these transcription factors on the MMP-induced EMT. In Aim 3, we will examine how MMP/ROS induce cellular aneuploidy and mitotic abnormalities through stimulation of centrosome amplification. We expect that by elucidating the chain of events in the induction of EMT and genomic instability by MMPs, we will be able to identify novel promising points for therapeutic intervention in breast cancer.